Selective control devices for disc grinders



R. E. PRICE 2,845,755

SELECTIVE CONTROL DEVICES FOR msc GRINDERS Aug; 5, 1958 Filed Nov. 9,1956 5 M RR Y m flw z m mH/ m A 2 A e B \T) Q S, \w M.

d. a m R4 SELECTIVE CONTROL DEVICES FOR DISC GRINDERS Ralph E. Price,Beloit, Wis., assignor to Gardner Machine Company, Beloit, Wis.

Application November 9, 1956, Serial No. 621,419

5 Claims. (Cl. 51--112) This invention relates to disc grinders,particularly to size control devices for such machines.

An object of this invention is to provide measuring devices directedagainst opposite sides of a workpiece as it emerges from between opposedgrinding discs for determining which requires adjustment for wear asindicated by oversize condition of the work.

In the drawing, numerals 11a and 11b indicate supporting members forannularly opposed abrasive discs 13a and 13b. The hydraulic motorconsisting of cylinders 40a and 40b serve to retract discs 13a and 13bfrom grinding position. Another motor consists of cylinders 60a and 60band pistons 62a and 62b which actuate two levers 70a and 70b to movesaid abrasive discs toward one another. The head ends of each of saidcylinders is always under constant air pressure.

Means is also provided for effecting incremental movement of each ofsaid discs including a motor having cylinders 30a and 30b and pistons32a and 32b for actuating pawls 28a and 28b and ratchets 27a and 27b.Said ratchets function through suitable gearing to rotate feed screws21a and 21b to advance said abrasive discs toward one another. The meansfor selectively controlling the flow of actuating fluid to opposite endsof cylinders 30:: and 30b consists of a pair of oppositely disposednozzles 45 and 46 adjacent the point of exit of the workpiece frombetween the grinding discs. A supply of air for said nozzles 45 and 46,which is provided through pressure regulating valves PR3 and PR2.respectively, is also connected to pressure switches PS3 and PS2respectively. As the workpieces emerge from the grinding discs and movepast said nozzles, they enter a space between guide members 51 and 52.After passing through said guide members, the workpieces must pass agauging device consisting of a stationary member 55 and a movableplunger member 56 of conventional construction for controlling theescape of air in accordance with the space between said members which isalso the size of the workpiece. Said plunger member 56 is connectedthrough a regulating valve PR1 to a supply of air which also acts on theair pressure switch PS1 when the escape of air from said plunger 56 isrestricted.

Operation When a workpiece W emerges from between the grinding discs, itis checked by nozzles 45 and 46. If the workpiece is closer to onenozzle than the other, indicating oversize due to wear of thecorresponding grinding disc, the air flowing from said nozzle will berestricted and the corresponding pressure switch will be actuated torates Patent 6 close one of the contacts .53 or 54 in the circuit to oneof the valve solenoids A or B. When said oversize workpiece passesbetween the members 55 and 56, the pressure operated switch PS1 isactuated to close a contact 57 to complete a circuit from L1 to contact53 of pressure switch PS3 or contact 54 of pressure switch PS2. ClosingPS3 or PS2 will complete a circuit to energize valve solenoids A or B toshift valves 3a or 3b to direct fluid under pressure to the rod end ofcylinders 30a or 3011. Pistons 32a or 32b through piston rods 28:: or28b and ratchets 27a or 27b will rotate feed screws 21a or 21b toadvance discs 13a or 13b in the direction of the other whereby torestore the operating surfaces of the discs to alignment with guides 51and 52 and spaced apart a distance equal to the desired thickness orsize of the workpiece.

If a workpiece surface is not sufficiently out of line to actuate eitherof the pressure switches PS2 or PS3 as it passes between the nozzles 45and 46, it may still cause an adjustment of one of the discs when itpasses through the gauge members 55 and 56 since this gauge is moresensitive than the nozzles.

If neither of the nozzles transmits a signal, there is no selection asto which disc is to be fed. However, under these circumstances, anysignal for feeding transmitted from the gauge member 56 acts to closecontact 57 and complete a circuit from L1 through the normally closedcontact 54 of PS2 to energize valve solenoid A and direct fluid underpressure through valve 3:: to the rod end of cylinder 30a to effect afeeding movement of wheel support 11a and disc 13a toward the opposingdisc 13b. This intermittent feeding of disc 13a will continue until thenozzles 45 or 46 indicate an out of alignment condition sufiicient tocause nozzle 46 to actuate pressure switch PS2 to close a contact in theline leading to valve solenoid B. Thus, when the slightly oversizeworkpiece passes through the gauge members 55 and 56, a circuit will becompleted through contact 57 of PS1 and normally closed contact 54 ofPS2 to said solenoid to shift valve 3a and direct fluid under pressureto the rod end of cylinder 30a. Piston 32a actuates ratchet 27a to turnfeed screw 21a to provide one or more increments of feed to disc 13a torestore the normal relation between the discs and the centerline of theworkpiece and the guide surfaces and thus assure proper size of theground workpiece.

If both discs 13a and 13b are worn sufficiently, the position of theworkpiece surfaces as the workpiece emerges from between said discs,will be such as to restrict the air from both of the nozzles 45 and 46.This will close contacts 53 and 54 so that when the work passes betweenmembers 55 and 56, contact 57 of pressure switch PS1 will complete thecircuit through both of the contacts 53 and 54 to energize valvesolenoids A and B. Valves 3a and 3b will thus be shifted to direct fluidunder pressure to the lower ends of cylinders 30a and 30b. Pistons 32aand 32b, through piston rods 28a and 28b and ratchets 27a and 27b, willrotate feed screws 21a and 21b to advance discs 13a and 13b toward oneanother whereby to restore the operating surfaces 'of said discs toalignment with guides 51 and 52.

I claim:

1. In a disc grinder having annularly opposed grinding discs, guideplates for guiding a workpiece as it emerges from between said discs,means for feeding each of said discs toward and from the other, controlmeans on both sides of a workpiece as it emerges from between thegrinding discs, said means serving to determine whether either or bothsides of a workpiece is in proper alignment with said guides and hence,whether either or both of said discs requires adjustment, means actuatedby said control means for effecting actuation of said feeding means toadjust one or both of said discs axially, a second control 3 elementco-acting with one side of a workpiece to detect oversize workpieces,means actuated by the second control element for completing a circuit toone or both of said feed actuating control means depending upon whetherone or both discs require adjustment.

2. In a disc grinder having annularly opposed grinding discs, eachhaving means for feeding one toward and from the other, control means atboth sides of a workpiece and responsive to the position of the worksurface while part of said surface is still being ground, said meansserving to determine whether one or both sides of a workpiece is inproper alignment and thus whether the discs are properly spaced andpositioned, means actuated by said control means for effecting operationof said feeding means to adjust one or both of said discs axially, asecond control element co-acting with a workpiece and positioned to beaffected by the workpiece only after said workpiece has emergedcompletely from between the grinding discs to detect oversizeworkpieces, and means actuated by the second control element forcompleting a circuit to one or both of said feed actuating control meansafter said workpiece is clear of the grinding discs.

3. In a disc grinder having annularly opposed grinding discs, eachhaving means for feeding one toward and from the other, a carrier fortransporting workpieces between said opposed discs for a grindingoperation, guide means in alignment with said grinding discs forreceiving workpieces as they emerge from between said discs, a controldevice having elements for coacting with opposite sides of a workpiecewhile part of said workpiece is still being ground, such control meansserving to determine whether either or both of said discs is worn beyondprescribed limits as evidenced by the lateral position and size of theemerging workpiece, means actuated by said control means for effectingoperation of said feeding means to adjust one or both of said discsaxially, a second control device co-acting with the workpiecesimmediately after they have passed said first control means andresponsive to oversize of workpieces to co-operate with said firstmentioned control means to actuate the feeding means for one or both ofsaid grinding discs depending upon whether said first control meansindicates the need for such adjustment by one or both of said discs.

4. In a disc grinder having annularly opposed grinding discs, eachhaving means for feeding one toward and from the other, control means atboth sides of a workpiece and responsive to the position of the worksurface while part of said surface is still being ground, said meansserving to determine whether one or both sides of a workpiece is inproper alignment and thus whether the discs are properly spaced andpositioned, means actuated by said control means for effecting operationof said feeding means to adjust one or both of said discs axially, asecond control element co-acting with a workpiece for detectingoversized workpieces and positioned so that a workpiece will passtherethrough only after said workpiece has emerged completely frombetween the grinding discs, means actuated by the second control elementfor completing a circuit to one or both of said feed actuating controlmeans after said workpiece is clear of the grinding discs.

5. In a disc grinder having annularly opposed grinding discs, means forrotatably supporting said discs, said disc supporting means beingslidably mounted on a bed member, each having means for feeding saiddiscs toward and from one another, means for actuating the feeding meansfor each of said supporting members to compensate for wear on thegrinding discs and thereby maintain a fixed space between said discs,means for controlling said feeding means comprising sensing devicesdirected to the opposite sides of a workpiece near the point where itemerges from the grinding discs, and means to delay the operation ofsaid feeding means by said sensing devices comprising another sensingdevice positioned to respond to a workpiece after it has passed saidfirst sensing device and emerged completely from the grinding discscomprising parallel contacts adapted to be actuated by said firstsensing device, and connections from each of said contacts through acontact actuated by said other contact to complete a circuit through oneor both of said first mentioned contacts.

References Cited in the file of this patent UNITED STATES PATENTS

